1. Field of the Invention
The present invention relates to a technology of a distributed power supply having plural power supply sections in a device.
2. Description of the Related Art
Transmission devices in recent years are integrated in high density to provide various services. As a result, power consumption of the transmission device has increased. Device configurations are required to be flexibly changeable depending on various service forms, to provide various client services. To realize that, the device is structured with a control system to control the overall device and a controlled system to provide the services. According to the configuration, changes in the service forms can be handled flexibly. For example, when a different service form is required, only the controlled system is required to be exchanged. Furthermore, a new service can be added even while the device is in operation.
The control system and the controlled system further facilitate function changes and exchanges by using printed circuit boards (PCB) prepared for each function. Each PCB providing a service requires a different power voltage and a different electric current, due to differences in functions and the like. The power consumption of the transmission device has been rising and more transmission devices have individual PCBs. Therefore, implementation of a distributed power supply method, rather than a conventional centralized power supply method, to supply power is increasingly used. In the centralized power supply method, the power supply is centralized in one location. In the distributed power supply method, the power is supplied to individual PCBs. The distributed power supply method includes an on-board power supply, provided in each PCB. Each PCB provides one wiring for a primary power supply of the on-board power supply. Each PCB monitors a power status, individually.
FIG. 6 is a block diagram of the transmission device using the distributed power supply method according to a conventional technology. A transmission device 1000 includes a main signal processing unit 1001 and a monitor control unit 1002. The main signal processing unit 1001 includes an active circuit 1003 and a backup circuit 1004. The active circuit 1003 and the backup circuit 1004 each include PCBs 1010 and 1011 for respectively different functions. A circuit processing PCB 1010 mainly converts an optical signal to an electric signal or converts the electric signal to the optical signal. A circuit switching PCB 1011 switches a main signal.
The primary power supply is supplied to the transmission device 1000 from an external source. The primary power supply is supplied to the on-board power supply 1020 of each of the PCB 1010, the PCB 1011, and the PCB 1012. The on-board power supply 1020 supplies a secondary power supply to the PCB 1010, the PCB 1011, and the PCB 1012, respectively.
A control system PCB 1012 within the monitor control unit 1002 includes a notification and control unit 1015. The control system PCB 1012 controls a conversion operation of the circuit processing PCB 1010 and controls a switching operation of the circuit switching PCB 1011 in the main signal processing unit 1001, using a monitor control signal. The control system PCB 1012 also performs an alarm notification to the outside when a circuit control is abnormal.
The PCB 1010, the PCB 1011, and the PCB 1012 individually monitor a primary power status. When the PCB 1010, the PCB 1011, or the PCB 1012 detects an occurrence of an abnormal state in the primary power supply, the PCB that detects the abnormal state individually performs a restarting process.
A conventional power supply includes a power supply unit. The power supply implements the centralized power supply method that supplies the secondary power supply to each PCB, and transmits a RESET signal to each PCB when an abnormal reduction in the power is detected (for example, Japanese Patent Laid-Open Publication No. 2002-35244).
A centralized power supply method in which power is collectively supplied to all PCBs causes waste or limits expandability in a transmission device including PCBs. If the transmission device has a controlled system that can correspond to changes in the services, power voltages and electric currents may become unnecessary because of the changes in services. If a PCB having a function corresponding to a new service is added, the power voltages or electric currents required by the PCB may not be provided. Moreover, power lines are required for each type of secondary power supply between a power supply unit of a centralized power supply and each PCB.
In addition, a normal recovery is often not performed after detection of a power supply abnormality in the distributed power supply method. FIG. 7A is a schematic for illustrating a normal operation state in the distributed power supply method. When an instantaneous interruption in the primary power supply occurs due to lightning damage or the like, only some of PCBs detect an abnormality in the primary power supply and restarts, because of differences in power lines within the device (differences in impedance and length) and individual differences between the PCBs. When the abnormality in the primary power supply is detected by the control system PCB 1012, as shown in FIG. 7A, the operation states of the restarted controlled system PCB 1010 and controlled system PCB 1011 are reconfigured and a service can be recovered, after the control system PCB 1012 is started.
FIG. 7B is a schematic for illustrating an abnormal operation state in the distributed power supply method. When only the controlled system PCB 1011 detects the abnormality in the primary power supply and restarts, and the control system PCB 1012 cannot detect the restarting of the controlled system PCB 1011, the control system PCB 1012 does not reconfigure the operation states of a controlled system PCB 1010 and the controlled system PCB 1011 to an operation state for normal operations. Therefore, the restarted controlled system PCB 1011 cannot make a transition into a normal operation state, and the service remains unavailable.
In a primary power supply monitoring, a power supply interruption for duration equal to or more than a predetermined time (for example, 1 millisecond (ms)) is always detected and the entire device is stopped. At the time of the power supply interruptions for duration less than a detectable time (for example, 51.2 microseconds (μs)), the device cannot be stopped due to circuit limitations and the like. When an instantaneous interruption for duration from the detectable time to the predetermined time occurs, whether each PCB stops depends on individual differences caused by capacitor elements and the like of each PCB. Therefore, some PCBs stop and restart, but some PCBs do not stop and continue running.
FIG. 8 is a timing chart for explaining an operation when the instantaneous interruption is detected in the conventional technology. When the instantaneous interruption occurs in the primary power supply (primary power voltage) for a time (T1) that is equal to or more than the detectable time and less than the predetermined time, the PCB detects the instantaneous interruption, supplies a secondary power supply (after an elapse of on-board power supply 1020 restart time T2, for example, T2=161 ms to 507 ms) normally, and supplies power. However, if the instantaneous interruption (primary power supply abnormality) is undetected by another PCB (X1), reset is not performed in the other PCB (X2). If the other PCB is the control PCB, the device does not restart and the operation state of the restarted PCB is not reconfigured. Therefore, the service remains unavailable in the restarted PCB. If the restarted PCB is disposed in an active circuit for communication, communication service remains unavailable even though the power supply being recovered.
To prevent the problem, an implementation of a method can be considered, in which the control PCB individually monitors a restart status of each PCB. However, in this case, each controlled system PCB is required to notify the control system PCB of the operation state via a dedicated monitor control line. Therefore, the control PCB is required to provide the dedicated monitor control line for each controlled PCB. In this case, unnecessary wirings may be formed depending on the configuration of the controlled system PCB. Wirings may also become insufficient when the number of PCB to be additionally monitored changes. In this method in which the control system PCB individually monitors each PCB, circuits and wirings tend to be wasted. Furthermore, the circuit size for monitoring tends to increase, expandability of diversion and the like becomes limited, and the monitoring becomes inefficient.
In the technology disclosed in the Japanese Laid-open Patent Publication No. 2002-35244, the abnormal power supply reduction is monitored only in the power supply unit. This is effective for monitoring the power voltage of the primary power supply, from the outside of the device to the power supply unit, and the secondary power supply in the power supply unit. A system reset is also possible. However, the power supply reaching the PCB that provides a service cannot be monitored. Therefore, as described above, only some of PCBs may restart when an instantaneous interruption in the primary power supply occurs due to lightning damage or the like, because of the differences in the power lines within the device and individual differences between the PCB. The restarted PCB cannot make a transition into the normal operation state and the service remains unavailable. For example, if only a voice control PCB is restarted, the control system PCB cannot detect the restart. Therefore, the system reset of the entire device remains uncontrolled.